Blends of poly(1,3-propylene 2,6-naphthalate)

ABSTRACT

Disclosed are physical blends of poly(1,3-propylene 2,6-naphthalate) polymer compositions with other polymers in which the concentration of poly(1,3-propylene 2,6-naphthalate) is from 1 to 99 mole %.

This application claims the benefit of provisional application60/098,675 filed Sep. 1, 1998.

FIELD OF THE INVENTION

This invention concerns physical blends of poly(1,3-propylene2,6-naphthalate) polymer compositions with other polymers in which theconcentration of poly(1,3-propylene 2,6-naphthalate) is from 1 to 99mole %.

TECHNICAL BACKGROUND OF THE INVENTION

This invention relates to blends of poly(1,3-propylene 2,6-naphthalate)polymers (referred to herein as 3GN polymers or 3GN) with otherpolymers.

U.S. Pat. No. 3,937,754 discloses a biaxially oriented polyethylene2,6-naphthalate (PEN) film which comprises PEN containing no more than10 mole % of non PEN forming components and 0.5 to 10% of a polyestercontaining at least 90 mole % of a homopolyester unit other than PEN,having a softening point at least 1° C. higher than its equilibriumsoftening point. Patentees teach that improvements in resistance tothermal degradation and Young's modulus are achieved after the softeningpoint of the PEN resin has decreased and before it decreases to a pointat least 1° C. higher than its equilibrium softening point. Thus,patentees teach that some, but not complete, reaction between thepolyesters is necessary to achieve their desired advantages.

It is an object of the present invention to provide physical blends inwhich essentially no reaction between polymer components occur.

SUMMARY OF THE INVENTION

The present invention relates to compositions comprising physical blendsof poly(1,3-propylene 2,6-naphthalate) polymer compositions with one ormore second polymers in which the concentration of 3GN is from 1 to 99mole % and in which essentially no reaction between the polymercomponents has taken place.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plot of Differential Scanning Calorimetry (DSC) data forvarious 3GN/3GT blends and pure 3GN and pure 3GT.

DETAILED DESCRIPTION OF THE INVENTION

3GN compositions of the present invention can be formed in immiscibleblends with one or more other polymers. For example, blends of 3GN withother polyesters, such as, for example, poly(ethylene terephthalate),poly(ethylene 2,6-naphthalate), poly( 1,3-propylene terephthalate)(3GT), or poly( 1,3-propylene isophthalate) and/or copolymers thereofcan be used. Other polymers which are suitable for forming immiscibleblends with 3GN include ethylene vinyl alcohol and copolymers thereof,aliphatic polyamides and copolyamides, partially aromatic polyamidecopolymers such as poly(1,3-xylylene adipamide), polyacetals such aspoly(oxymethylene), polycarbonate, acrylic polymers such aspoly(methylmethacrylate), and polyolefins and copolymers thereof such aspolypropylene and polystyrene. Most preferred compositions are thefollowing blends: poly(1,3-propylene 2,6-naphthalate) with poly(ethyleneterephthalate); poly(1,3-propylene 2,6-naphthalate) withpoly(1,3-propylene terephthalate); poly(1,3-propylene 2,6-naphthalate)with poly(1,3-propylene isophthalate); and poly(1,3-propylene2,6-naphthalate) with poly(ethylene 2,6-naphthalate), wherein theconcentration of poly(1,3-propylene 2,6-naphthalate) is from 1 to 99mole %.

The blends can be prepared using methods known in the art for preparingimmiscible blends, such as mixing melts continuously in a single or twinscrew extruder, or batch-wise in Banbury mixers. The blends according tothe invention contain at least about 1 mole % to about 99 mole % 3GN. Byimmiscible it is meant that a differential scanning calorimetry (DSC)scan of the blends shows multiple glass transition temperatures (T_(g)),each T_(g) being characteristic of the individual polymer components ofthe blend, as compared to miscible blends which exhibit a single,composition-dependent T_(g).

When preparing 3GN blends with polyesters or other polymers that canreact with 3GN during melt blending, such as polyamides, the blendshould be held in the melt no more than about 10 minutes in order tominimize the degree of transesterification and copolymer formation. Themelt blending temperature should be no higher than 30° C. greater thanthe highest melting component of the blend. Preferably, there is lessthan about 5 mole % copolymer formed by transesterification, asindicated by an absence of peaks in the proton and ¹³C nuclear magneticresonance spectra (detection sensitivity=1-2 mole %) other than thosecorresponding to the individual polymer components.

The utility of the compositions of the present invention is in themanufactures or formed articles, especially films. Certain of thecompositions are especially useful in the manufacture of biaxiallyoriented films.

The poly(1,3-propylene 2,6-naphthalate) component of the compositions ofthe present invention can be prepared by transesterification of adialkyl ester of 2,6naphthalene dicarboxylic acid and 1,3-propanediol ordirect esterification of 2,6-naphthalene dicarboxylic acid and1,3-propanediol followed by polycondensation.

For example, in a batch process, a C₁-C₄ dialkyl ester of2,6-naphthalene dicarboxylic acid and 1,3-propanediol are reacted in aninert atmosphere such as nitrogen in a mole ratio of about 1:1.2 toabout 1:3.0 in the presence of a transesterification catalyst at atemperature between about 170° C. and 245° C. at atmospheric pressure toform a monomer and a C₁-C₄ alkanol corresponding to the C₁-C₄ alkanolcomponents of the dialkyl ester of 2,6-naphthalene dicarboxylic acid.The C₁-C₄ alkanol is removed as it is formed during the reaction.Examples of transesterification catalysts include compounds ofmanganese, zinc, calcium, cobalt, titanium, and antimony such asMn(acetate)₂, Zn(acetate)₂, Co(acetate)₂, tetrabutyl titanate,tetraisopropyl titanate, and antimony trioxide. The resulting reactionproduct, comprising bis(3-hydroxypropyl) 2,6-naphthalate monomer andoligomers thereof, is then polymerized at temperatures between about240° C. and 280° C. under a reduced pressure of below about 30 mm Hg inthe presence of a polycondensation catalyst, with removal of excess1,3-propanediol, to form 3GN having an inherent viscosity in the rangeof 0.2-0.8 deciliter/gram (dL/g). Examples of suitable polycondensationcatalysts include compounds of antimony, titanium, and germanium such asantimony trioxide, tetrabutyl titanate, tetraisopropyl titanate. Atitanium catalyst can be added prior to transesterification as both thetransesterification and polycondensation catalyst. Thetransesterification and polycondensation reactions can also be carriedout in continuous processes.

Other comonomers can be included during the preparation of the 3GN. Forexample, one or more other diols (other than 1,3-propanediol),preferably in an amount up to about 10 mole % based on total diol(including 1,3-propanediol and the other diol), and/or one or more otherdicarboxylic acid or C₁-C₄ dialkyl ester of a dicarboxylic acid (otherthan 2,6-naphthalene dicarboxylic acid and C₁-C₄ diesters thereof,preferably in an amount up to about 10 mole % based on the total diacidor dialkyl ester (including the 2,6-naphthalene dicarboxylic acid orC₁-C₄ diakyl ester thereof and the other dicarboxylic acid or C₁-C₄dialkyl ester thereof) can be added before or during the esterificationor transesterification reaction. Examples of comonomers which can beused include terephthalic acid or isophthalic acid and C₁-C₄ diestersthereof, and C₁-C₁₀ glycols such as ethylene glycol, 1,4-butanediol, and1,4-cyclohexane dimethanol.

The inherent viscosity of the 3GN can be further increased using solidphase polymerization methods. Particles of 3GN having an inherentviscosity of about 0.2-0.7 dL/g can generally be solid phased to aninherent viscosity of 0.7-2.0 dL/g by first crystallizing at atemperature of between about 165° C. and 190° C. for at least about 6hours, preferably about 12-18 hours, followed by solid phasepolymerizing under an inert atmosphere, such as a nitrogen purge, at atemperature of between about 190° C. to 220° C., preferably betweenabout 195° C. to 205° C., for at least about 12 hours, however, the timeperiod can range from 16-48 hours. The solid phase polymerization of the3GN particles may also be conducted under a vacuum of about 0.5-2.0 mmHg.

The 3GN preferably has an inherent viscosity in the film-forming range,generally between about 0.2-1.0 dL/g, more preferably 0.5-0.9 dL/g, mostpreferably 0.55-0.85 dL/g.

EXAMPLES Test Methods

Inherent viscosity was measured in 60 wt % phenol/40 wt %1,1,2,3-tetrachloroethane at 30° C. at a polymer concentration of 0.50%by weight, according to the procedure of ASTM D-4603-91.

Melting point, crystallization temperature and glass transitiontemperature were determined using the procedure of ASTM D-3418 (1988)using a DuPont DSC Instrument Model 2100. The heating and cooling rateswere 10° C./min.

Density was measured in grams per cubic centimeter (g/cc) using thedensity-gradient method, according to ASTM D-1505-85.

Number average and weight average molecular weights (Mn and Mw) weremeasured by size exclusion chromatography using hexafluoroisopropanol asthe solvent.

Nuclear magnetic resonance (NMR) spectra of 3GN blends were measured bydissolving the blends in deuterated hexafluoroisopropanol. Proton and¹³C NMR were measured on a Bruker high resolution NMR spectrometer. ¹³Cspectra at 400 Hz were collected with a 30-second relaxation delay andinverse-gated decoupling.

Experiment 1

This example describes the synthesis of poly (1,3-propylene2,6-naphthalate) (3GN).

Dimethyl 2,6-naphthalenedicarboxylate (36.36 kg, 149 moles) (purchasedfrom Amoco Chemical Company, with offices in Chicago, Ill.) and1,3-propanediol (purchased from Degussa, with offices in RidgefieldPark, N.J.) (24.91 kg, 327.8 moles) were reacted under atmosphericpressure under nitrogen in the presence of 6.1 g of Tyzor® titaniumtetraisopropoxide catalyst (100 ppm catalyst based on the total weightof ingredients and catalyst) (commercially available from E. I. du Pontde Nemours and Company, Wilmington, Del.) in 300 ml 1,3-propanediol inan agitated vessel heated with a hot oil system. The vessel was heatedto 242° C. over a period of about 330 minutes. When the temperature ofthe reaction mixture reached 188° C., methanol started to evolve and wasremoved as a condensate by distillation as it was formed. Methanolevolution continued until about 180 minutes after the start of thereaction, when the temperature reached about 213° C. Excess1,3-propanediol started to evolve, and was collected as a condensate bydistillation, when the temperature reached about 217° C. and continuedto evolve for another 150 minutes as the mixture was heated to 242° C.

The pressure in the reaction vessel was then reduced from aboutatmospheric to about 10 mm Hg while the temperature was increased toabout 275° C. over a period of about 90 minutes. The pressure was thenreduced further to 0.5 mm Hg while the temperature was raised to 280° C.The polymerization was allowed to proceed an additional 30 minutes toobtain a polymer having an inherent viscosity of 0.56 deciliter/gram(dL/g).

The polymer obtained was translucent white in color and was identifiedas poly (1,3-propylene 2,6-naphthalate) by analyzing the peaks in theC-13 NMR using hexafluoroisopropanol solvent. The polymer had a meltingpoint of 201-203° C., a crystallization temperature of 166° C., and aglass transition temperature of 79° C. The inherent viscosity thepolymer was 0.56 dL/g, with a number average molecular weight (M_(n)) of22,000 and a weight average molecular weight (M_(w)) of 36,000.

Example 1

This example describes the preparation a 60 mole % blend of 3GN withpoly(1,3-propylene terephthalate).

27.1 g (0.106 mole) of the 3GN prepared in Experiment 1 and 12.9 g(0.063 mole) of poly(1,3-propylene terephthalate) (3GT) having aninherent viscosity of 0.9 dL/g synthesized using the conditionsdescribed in J. Polym. Science A-1, (4), 1851-1859 (1966) were meltblended at 250° C. for 8 minutes under a nitrogen atmosphere in aPlasti-corder mixer (Type REE 230 V8 5 amp, made by BrabenderInstruments Inc., South Hackensack, N.J.) at 100 rpm rotating speed. Theresultant mixture was pulverized to about 20 mesh in a laboratorygrinder and was compression molded at 250° C. for 2 minutes and then aircooled to room temperature to form an opaque pressed film of 6-7 mil(0.15-0.18 mm) thickness.

Nuclear magnetic resonance (NMR) analyses of the 3GN/3GT film showedthat all of the NMR peaks observed were attributed to the individualpolymer components, with no extra peaks indicating that there wassubstantially no co-polymerization as a result of ester interchange.Differential scanning calorimetry (DSC) showed two glass transitiontemperatures (Tg), 73° C. and 45° C., and two melting points Tm, 203° C.and 228° C., corresponding respectively to the Tg and Tm of the original3GN and 3GT.

Example 2,3,4

Using the materials used in Example 1 and the melt blending methods ofExample 1, blends of 3GN and 3GT in the ratios of 80:20, 40:60, and20:80, respectively, were prepared. In all cases, nuclear magneticresonance (NMR) analyses of the 3GN/3GT film showed that all of the NMRpeaks observed were attributed to the individual polymer components,with no extra peaks indicating that there was substantially noco-polymerization as a result of ester interchange. Differentialscanning calorimetry (DSC) showed two glass transition temperatures (Tg)(See Table 1), and two melting points Tm (See Table 1), correspondingrespectively to the Tg and Tm of the original 3GN and 3GT.

TABLE 1 Thermal Properties of 3GT/3GN Blends All Temperatures in ° C.Mole Ratio Sample 3GN/3GT Tg₁ Tg₂ Tm₁ Tm₂ Control 1 100/0  72 — 203 —Example 2 80/20 47 71 203 227 Example 1 60/40 45 73 203 228 Example 340/60 56 74 203 229 Example 4 20/80 56 75 202 229 Control 2  0/100 53 —230 —

Example 5

This example describes the preparation of pressed films of a 60 mole %blend of 3GN with poly(ethylene terephthalate).

28.1 g (0.110 mole) of 3GN as prepared in Experiment 1 and 11.9 g (0.062mole) of PET (MYLAR® X299, 0.8 dL/g) (available from E. I. du Pont deNemours and Company, Wilmington, Del.) were melt blended at 280° C. andpulverized using the procedure described in Example 1. The blend wasthen compression molded at 280° C. for 2 minutes and then air cooled toform an opaque film of 6-7 mil (0.15-0.18 mm) thickness.

NMR analyses of the 3GN/PET film showed that all of the NMR peaksobserved were attributed to the individual polymer components, with noextra peaks indicating that there was substantially no copolymerizationas a result of ester interchange. DSC showed that the Tg of the 3GN andPET components were very close and overlapped at about 76.5° C. Therewere two melting peaks at 201° C. and 243° C., corresponding to themelting points of the original 3GN and PET, respectively.

What is claimed is:
 1. A composition comprising a physical blend, inwhich essentially no reaction has taken place, of (a) from 20 mole % to80 mole % poly(1,3-propylene 2,6-naphthalate) polymer composition with(b) from 80 mole % to 20 mole % one or more second polymers selectedfrom the group consisting of poly(ethylene terephthalate) andpoly(1,3-propylene terephthalate) or copolymers thereof.
 2. Thecomposition of claim 1 for which a differential scanning calorimetry(DSC) scan of the blend shows multiple glass transition temperatures(T_(g)), each T_(g) being characteristic of the individual polymercomponents of the blend, as compared to miscible blends which exhibit asingle, composition-dependent T_(g).
 3. The composition of claim 2 forwhich there is less than about 5 mole % copolymer formed bytransesterification of the poly(1,3-propylene 2,6-naphthalate) polymercomposition with the one or more second polymers, as indicated by anabsence of peaks in the proton and ¹³C nuclear magnetic resonancespectra (detection sensitivity=1-2 mole %) other than thosecorresponding to the individual polymer components.
 4. The compositionof claim 3 which has been melt blended at a temperature no higher than30° C. greater than the highest melting component of the blend.
 5. Thecomposition of claim 4 which has been held in the melt no more thanabout 10 minutes.
 6. The composition of claim 5 wherein thepoly(1,3-propylene 2,6-naphthalate) polymer is prepared with (a) up toabout 10 mole %, based on total diol, of one or more other diols (otherthan 1,3-propanediol) and/or (b) up to about 10 mole %, based on thetotal diacid or dialkyl ester (including the 2,6-naphthalenedicarboxylic acid or C₁-C₄ dialkyl ester thereof and the otherdicarboxylic acid or C₁-C₄ dialkyl ester thereof), of one or more otherdicarboxylic acid or C₁-C₄ dialkyl ester of a dicarboxylic acid (otherthan 2,6-naphthalene dicarboxylic acid and C₁-C₄ diesters thereof). 7.The composition of claim 6 in the form of a film.
 8. The composition ofclaim 7 wherein the film is a biaxially oriented film.
 9. Thecomposition of claim 1 for which there is less than about 5 mole %copolymer formed by transesterification of the poly(1,3-propylene2,6-naphthalate) polymer composition with the one or more secondpolymers, as indicated by an absence of peaks in the proton and ¹³Cnuclear magnetic resonance spectra (detection sensitivity=1-2 mole %)other than those corresponding to the individual polymer components. 10.The composition of claim 1 which has been melt blended at a temperatureno higher than 30° C. greater than the highest melting component of theblend.
 11. The composition of claim 10 which has been held in the meltno more than about 10 minutes.
 12. The composition of claim 1 whereinthe poly(1,3-propylene 2,6-naphthalate) polymer is prepared with (a) upto about 10 mole %, based on total diol, of one or more other diols(other than 1,3-propanediol) and/or (b) up to about 10 mole %, based onthe total diacid or dialkyl ester (including the 2,6-naphthalenedicarboxylic acid or C₁-C₄ dialkyl ester thereof and the otherdicarboxylic acid or C₁-C₄ dialkyl ester thereof), of one or more otherdicarboxylic acid or C₁-C₄ dialkyl ester of a dicarboxylic acid (otherthan 2,6-naphthalene dicarboxylic acid and C₁-C₄ diesters thereof). 13.The composition of claim 1 wherein the one or more second polymers isthe poly(1,3-propylene terephthalate).
 14. The process of claim 13wherein the composition has less than about 5 mole % copolymer formed bytransesterification of the poly(1,3-propylene 2,6-naphthalate) polymercomposition with the one or more second polymers, as indicated by anabsence of peaks in the proton and ¹³C nuclear magnetic resonancespectra (detection sensitivity=1-2 mole %) other than thosecorresponding to the individual polymer components.
 15. The compositionof claim 1 wherein the one or more second polymers is the poly(ethyleneterephthalate).
 16. The composition of claim 1 in the form of a film.17. The composition of claim 16 wherein the film is a biaxially orientedfilm.
 18. A process of preparing the composition of claim 1 comprisingproviding the poly(1,3-propylene 2,6-naphthalate) polymer compositionand the one or more second polymers, and melt blending them at atemperature no higher than 30° C. greater than the highest meltingcomponent of the blend so that essentially no reaction takes placebetween the poly(1,3-propylene 2,6-naphthalate) polymer composition andthe one or more second polymers.
 19. The process of claim 18 wherein thecomposition is held in the melt no more than about 10 minutes.
 20. Theprocess of claim 19 wherein the composition is such that a differentialscanning calorimetry (DSC) scan of the blend shows multiple glasstransition temperatures (T_(g)), each T_(g) being characteristic of theindividual polymer components of the blend, as compared to miscibleblends which exhibit a single, composition-dependent T_(g).